Research On Key Technologies Of Power Detection And Precision Drive In All-Solid-State Laser

With the growth of economy,the influence of environmental pollution on people's production and quality of life is increasing gradually.In recent decades,atmospheric detection lidar has been increasingly applied to the field of atmospheric pollution monitoring.As an important structure of atmospheric detection lidar,laser directly affects the working performance of lidar.In order to improve the performance of lidar,this paper takes an all-solid-state laser as the platform.On the one hand,it is hoped that the stability of laser output can be improved,and on the other hand,it is hoped that the power output of the laser can be detected in real time to provide a reasonable reference index for the adjustment of the laser.The important research work of this paper is as follows:(1)According to the characteristics of the narrow pulse width and high repetition frequency of the laser output pulse,a photoelectric conversion and pre-amplification circuit is designed to complete the conversion from optical pulses to electrical pulses;A narrow pulse peak hold circuit which was based on integrated operational amplifiers was designed to complete the signal conditioning of the narrow laser pulse,effectively broaden the pulse width,and facilitate the use of low-cost low-speed analog-to-digital converter(ADC)acquisition;The synchronous trigger circuit and single-chip microcomputer were used to complete the design of the acquisition sequence and the detection of the laser output power;In order to improve the performance of the laser power detection system,the noise of the system is analyzed,the stability of the detection circuit is improved,and the design of the circuit board is optimized.(2)Working principle and failure mechanism of the semiconductor laser were analyzed;The deep negative feedback technology of the hardware were combined with the closed-loop control of the software to improve the stability of the constant current drive output of the semiconductor laser pump source;Based on the failure mechanism of semiconductor lasers,over-current and over-temperature protection circuit,slow-start protection circuit and anti-shock protection circuit were designed to ensure the safety and stability of the semiconductor laser during the working process,and avoid damage.(3)Influence of temperature on the laser's work was analyzed;A high-precision temperature acquisition circuit and a stable,reliable thermoelectric cooler(TEC)drive circuit were designed,and also added over-current and over-temperature protection to prevent damage to the TEC during operation;Based on the thermoelectric cooler(TEC)temperature control system model,the temperature transmission process was analyzed and the system transfer function of the temperature control model is calculated;The unknown parameters of the system transfer function of the temperature control model are identified by the particle swarm optimization algorithm;A fuzzy adaptive PID control algorithm is proposed to improve the accuracy of temperature control,and Simulink was used to simulate and analyze the control system.